Is glomalin an appropriate indicator of forest soil reactive nitrogen status?

Abstract

In this paper we address total glomalin‐related soil protein (T‐GRSP) as a possible indicator of differences in forest soils related to reactive nitrogen and forest composition. We focused especially on the relationship between T‐GRSP (g kg−1), soil organic carbon (SOC), and reactive nitrogen (Nr) availability among different categories of temperate forests and different horizons. Our study included 105 sampling sites divided into 5 categories, which vary in elevation and tree species composition (coniferous, deciduous, mixed). We detected significantly higher T‐GRSP and SOC in the F+H horizon under conifers. We assume that this observation might be attributed to suppression of decomposition of T‐GRSP and SOC by nature of coniferous litter. The lack of significant differences in T‐GRSP/SOC among the categories and the positive correlations between T‐GRSP and SOC in most of the categories confirmed the strong relationship of T‐GRSP with SOC. We found a significantly higher content of T‐GRSP in the F+H horizon for all studied forest categories. However, the contribution of T‐GRSP to SOC is significantly higher in the A horizon, which might be caused by stabilization of glomalin by mineral fraction, including clay minerals or by the belowground origin of glomalin. We found the increase of SOC with increasing Nr in the A horizon for most categories of forest. T‐GRSP follows this trend in the case of deciduous forests (decid), mixed forest (mixed), and mountain forests (mount). On the other hand, we detected a decrease of T‐GRSP with increasing Nr in the F+H horizon of coniferous forests (conif). Moreover the T‐GRSP/SOC decreases with the increase of Nr in the A horizon of conif, mixed and mount, which points to the higher sensitivity of forest with prevalence of coniferous trees. Our observations have confirmed an ecosystem‐specific relationship between T‐GRSP, SOC and Nr. We concluded that T‐GRSP in combination with T‐GRSP/SOC has the potential to reveal qualitative changes in soil organic matter (SOM) connected with increasing Nr.

Biological and chemical attributes of soils under forest species in Northeast Brazil

“…(r = 0.81). This direct relationship between the levels of glomalin and SOC has already been observed in soils under tree canopies (Vasconcellos et al 2016;Rotter et al 2017;Zang et al 2017). The relationship between The elements P, K, Na, Cu, Fe, Mn and Zn were extracted with Mehlich-1; Ca and Mg were extracted with KCl (mol L -1 ).…”

“…The leaf litter deposition and the microenvironments in the vegetation coverage under these last two species may be favorable to AM fungi activity, microorganisms responsible for the production and deposition of glomalin in the rhizosphere. It is also possible that the quality of the leaf litter affected the decomposition rates of the organic matter, corroborating Joly et al (2017), as well as the glomalin content (Rotter et al 2017) in the soil. Silva et al (2014) noted some factors which could be related to the production or deposition of this protein by the AM fungi in plantations and in non-forested areas.…”

“…Glomalin is a glycoprotein produced by arbuscular mycorrhizal (AM) fungi, (components of cellular walls of hyphae and spores) (Wright et al 1996;Rillig 2004;Driver et al 2005), liberated in the soil after the decomposition and senescence of these fungi (Driver et al 2005). There is a direct relationship between GRSP, organic carbon content, and the stability of soil aggregates (Gispert et al 2013;Rotter et al 2017), and this affects nutrient cycles, water flow, microbial activities and plant development (Six and Paustian 2014) contributing to the sustainability of agroecosystems.…”

A critical review of 25 years of glomalin research: a better mechanical understanding and robust quantification techniques are required

“…Another benefit attributed to 'glomalin' is soil carbon deposition and subsequent sequestration. Glomalin-related SPs are thought to represent c. 20% of the soil organic carbon and aid carbon sequestration by stabilising soil aggregates (Preger et al, 2007;Rotter et al, 2017;Singh et al, 2020). Some studies have reported that glomalin-related SPs are more recalcitrant than other forms of soil organic matter, including general AMF necromass, but the reason for this is unexplored (Rillig et al, 2001;Preger et al, 2007;Zhang et al, 2017).…”

Spatial Distribution of Glomalin-related Soil Proteins in Coniferous and Broadleaf mixed Temperate Forest

“…Meanwhile, GRSP is an important cementing agent in the formation of soil aggregates, which plays a major role in maintaining soil organic carbon (SOC) pool (Rillig et al, 2001;Wright et al, 2007), which contributed to SOC accumulation with more than 20 times higher than microbial biomass (Rillig et al, 2001;Godbold et al, 2006;Prescott, 2010;Guo, 2013). In addition, GRSP is one of the indicators of active nitrogen along with SOC (Rotter et al, 2017). The GRSP in soil is classified into the total GRSP (TG) and the easily extracted GRSP (EEG) based on the different extracted methods (Wright et al, 1998b;Rillig et al, 2001).…”